Piston for an internal combustion engine

Abstract

A piston for an internal combustion engine of the type presenting circumferential grooves ( 10 ), each groove ( 10 ) housing a respective piston ring ( 20 ), at least one first upper groove ( 10 ) presenting a profile having upper and lower lateral walls ( 11, 12 ) radially outwardly inclined towards the piston top by an angle of inclination such as to compensate, at least partially, the deformations to which the piston is submitted when in a critical higher load operational condition, in order to maximize the distribution of the seating contact between at least one of the upper and lower lateral walls ( 21, 22 ) of the piston ring ( 20 ) and an adjacent lateral wall ( 11, 12 ) of the groove ( 10 ), as well as to minimize the wear that determines the useful life of the groove ( 10 ).

1 . A piston for an internal combustion engine of the type presenting circumferential grooves ( 10 ), each groove ( 10 ) housing a respective piston ring ( 20 ), characterized in that at least one first upper groove ( 10 ) presents a profile having an upper lateral wall ( 11 ) and a lower lateral wall ( 12 ), which are radially outwardly inclined towards the piston top by an angle of inclination such as to compensate, at least partially, the deformations to which the piston is submitted when in a critical higher load operational condition, in order to maximize the distribution of the seating contact between at least one of the upper and lower lateral faces ( 21 ,  22 ) of the piston ring ( 20 ) and an adjacent lateral wall ( 11 ,  12 ) of the groove ( 10 ), as well as to minimize the wear that determines the useful life of the groove ( 10 ).  
   
   
       2 . The piston as set forth in  claim 1 , characterized in that the maximization of the contact distribution is achieved between a lower lateral wall ( 12 ) of the groove ( 10 ) and an adjacent lower lateral face ( 22 ) of the piston ring ( 20 ).  
   
   
       3 . The piston as set forth in  claim 2 , characterized in that the condition of maximization occurs when the lower lateral wall ( 12 ) of the groove ( 10 ) is situated on a plane that is substantially orthogonal to the longitudinal axis of the piston under operation conditions.  
   
   
       4 . The piston as set forth in  claim 2 , characterized in that the first groove ( 10 ) has its upper and lower lateral walls ( 11 ,  12 ) parallel to each other.  
   
   
       5 . The piston as set forth in  claim 2 , characterized in that the piston ring ( 20 ) has its upper and lower lateral faces ( 21 ,  22 ) parallel to each other.  
   
   
       6 . The piston as set forth in  claim 1 , characterized in that the angle of inclination for each groove ( 10 ) is defined as a function of the mechanical and thermal characteristics of the piston ring ( 20 ), of the piston, and of the material that forms the latter.  
   
   
       7 . The piston as set forth in  claim 6 , characterized in that the thermal characteristics of the piston are determined by the coefficients of thermal transmission and thermal expansion of the piston material.  
   
   
       8 . The piston as set forth in  claim 7 , characterized in that the mechanical characteristics of the piston ring ( 20 ) are determined by the torsion and rigidity stiffness of the respective cross-section of the piston ring ( 20 ).  
   
   
       9 . The piston as set forth in  claim 8 , characterized in that the mechanical characteristics are determined taking into account the relative movements between the piston ring ( 20 ) and the respective groove ( 10 ), and the superficial roughness in each of the parts defined by the piston ring ( 20 ) and groove ( 10 ).  
   
   
       10 . The piston as set forth in  claim 1 , characterized in that the angle of inclination is defined from about 5-30 minutes.  
   
   
       11 . The piston as set forth in  claim 10 , characterized in that the angle of inclination is preferably defined from about 5-15 minutes.